build: do not "exit" a script meant to be "source"d

Running exit in a script meant to be sourced means the user shell will
exit, which prevents seeing the error message, and is generally very
annoying.
Fix the "android-configure" script to use "return" instead of "exit".

PR-URL: #35520
Fixes: #35519
Reviewed-By: Michaël Zasso <targos@protonmail.com>

android-configure

@@ -10,7 +10,7 @@
 
 if [ $# -ne 3 ]; then
   echo "$0 should have 3 parameters: ndk_path, target_arch and sdk_version"
-  exit 1
+  return 1
 fi
 
 NDK_PATH=$1
@@ -44,7 +44,7 @@ case $ARCH in
         ;;
     *)
         echo "Unsupported architecture provided: $ARCH"
-        exit 1
+        return 1
         ;;
 esac
 
@@ -58,7 +58,7 @@ major=$(echo $host_gcc_version | awk -F . '{print $1}')
 minor=$(echo $host_gcc_version | awk -F . '{print $2}')
 if [ -z $major ] || [ -z $minor ] || [ $major -lt 6 ] || [ $major -eq 6 -a $minor -lt 3 ]; then
   echo "host gcc $host_gcc_version is too old, need gcc 6.3.0"
-  exit 1
+  return 1
 fi
 
 SUFFIX="$TOOLCHAIN_NAME$ANDROID_SDK_VERSION"